Circuit and apparatus for operating electric discharge lamps



March 9, 1937. J. PETERSON 2,073,527

CIRCUIT AND APPARATUS FOR OPERATING ELECTRIC DISCHARGE LAMPS Filed Feb. 28, 1935 High Pressure Mercury Vapor Lamp Invent or: Justin Peterson is Aftorheg.

45 is materially higher than the poten Patented Mar. 9, 1937 CIRCUIT AND APPARA PATENT OFFICE TUS FOR OPERATING ELECTRIC DISCHARGE LAIHPS Justin Peterson,

eral Electric York Saugus,

Mass, assignor to Gen- Company, a corporation of New Application February 28, 1935, Serial No. 8,632

3 Claims.

My invention relates to electric discharge lamps, and more particularly to a circuit and apparatus for operating them.

One object of my invention is to provide an improved starting apparatus for electric-discharge lamps when operated on series circuits.

Another object of my invention is to provide means for improving the operation of the lamp, particularly by reducing the outage time subsequent to a current interruption.

For a better understanding of my invention, together with other and further objects thereof, reference is had to the following description,

' taken in connection with the accompanying l5 drawing, and its scope will be pointed out in the appended claims.

In the attached drawing, I illustrate diagrammatically my invention as applied to electricdischarge lamps of the type disclosed, for example, in U. S. Patent No. 1,948,261, and assigned to the assignee of the present invention. These lamps are commonly known as the high pressure mercury lamps, because during operation the mercury vapor pressure in the lamp rises to a value which is substantially equal to atmospheric pressure. The single figure of the drawing illustrates a transformer I having its primary winding 2 connected into a constant current circuit. The secondary winding 3 of this transformer is connected to electrodes 4 and 5 respectively of a discharge lamp 6 and is protected by an insulating film cutout I.

In accordance with my invention the winding 8 of an ionizing transformer 9 is connected so as to carry during operation the full load current between the electrodes 4, 5 and the winding 3. The secondary winding ID of this transformer is connected across the electrodes 4 and 5 of the lamp having in series therewith the operating coil H of a relay l2. This circuit may be traced from electrode 4 through conductors l3 and I 4, winding I ll, conductor l5, relay coil ll, conductor l6 and electrode 5. When thus connected the potential of the secondary of the transformer 9 tial of I the secondary of the transformer l.

The relay i2 is provided with a movable contact arm I! which assumes a lower position when the coil I0 is deenergized or is energized insuificiently to lift its armature l8 to which the contact arm I! is attached, and assumes an upper position when the coil l l is fully energized. In. the lower position contact arm I1 engages fixed contacts I 9 and 20 and thereby closes a circuit including the transformer windings 8 and 3 only.

This circuit may be traced from winding 3, conductor 2i, contact 20, contact arm l'l, contact l9, conductors 22 and I3, winding 8 and conductor 23 to Winding 3. If the primary winding 2, is, therefore, energiz winding 3 energizes only 5 the primary winding 8 of the transformer 9. The secondary winding I!) being connected to electrodes 4 and 5 across the discharge lamp 6 produces an ionizing potential which gradually breaks down the resistance of the lamp and 10 thereby builds up the current through the lamp. When this current flow reaches a predetermined value, the coil ll moves its armature I 8 and the contact arm I! to the upper position to engage contact 24 while still engaging with the fixed 15 contact 20. In this position of the contact arm I 'l the winding 3 is connected directly across the electrodes 4 and 5. The circuit'may be traced from winding 3, conductor 2!, contact 20, contact arm l1, contact 24 and conductor is.

The connections between electrode 4 and winding 3 remain unchanged, and the winding 8 now carries the full lamp current. The secondary circuit of this transformer 9 also remains unchanged and the secondary winding I 0 is con- 25 nected across the electrodes 4 and 5 during operation. In the preferred arrangement of this apparatus this secondary potential is during starting considerably higher than the operating potential. In one of the lamps having an oper- 30 ating voltage of to volts the starting potential used is between 300 and 400 volts. The transformer is made of such high reactance that the current flow, when the winding I0 is connected across the winding 3, is only sufllcient to 35 maintain the relay contact arm IT in its upper position and in engagement with the fixed contacts 20 and 24. For example, it may be of the order of 30 to 40 milliamperes. In this manner the ionizing action during operation is negligible, 40 but during fluctuations of current or temporary interruptions thereof the contact arm I I is moved to its lower position to engage fixed contacts l9 and 20 and thereby disconnects the lamp from winding 3 and closes the circuit through winding 5 8. Upon a reenergization oi the transformer the ionizing potential is therefore immediately available.

In the high pressure available, the vapor mercury lamps now pressure during normal op- 50 eration of the lamp is approximately equal to atmospheric pressure. A momentary interruption of current, therefore, sufiicient to interrupt the discharge in the lamp causes an interruption of operation until this pressure has fallen to substantially initial pressure obtained at ambient temperature. It has heretofore been necessary to wait for the lamp to cool down to substantially ambient temperature. before the lamp could be started. With my arrangement as above described the time between interruption and restart has been considerably reduced since the cooling rate at the high operating temperature is high. The ionizing potential breaks down the tube resistance at a pressure greatly in excess of that obtained at ambient temperature and therefore the time required to cool the tube through the latter part of the temperature difference, above ambient, is eliminated.

Another advantage of the above-described circuit is that a breaking down of the protective devices such as insulating film cut-out i is prevented. When current in the series circuit is interrupted only long enough to stop operations of the lamp 5, the resistance of the lamp builds up immediately, and unless some by-pass is provided for the series transformer, a voltage will be built up across the terminals of the lamp of such magnitude that either a flash-over between terminals occurs or the protective device is broken down, and, thereby, the lamp is shunted out of circuit. To put such lamps back into service, it requires the service of an attendant who would have to replace the protective device. With my arrangement, the relay H operates when the current fiow ceases, a predetermined constant load is thereby placed upon the series transformer, and, simultaneously, a predetermined ionizing voltage is placed across the lamp.

F This ionizing voltage is, of course, of such magnitude that the most advantageous starting condition for the lamp is obtained.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination, an electric discharge lamp, a transformer for supplying operating current and a second transformer for supplying ionizing current to said lamp, and means responsive to the current supplied by said second transformer for effecting an energization of said lamp by said second transformer alone during the starting period of said lamp and for connecting said first transformer to said lamp during normal operation thereof.

2. In combination, an electric discharge lamp, a transformer for supplying operating current thereto and having a substantially constant current in its primary circuit, an ionizing transformer having a primary winding connected in series with said lamp during normal operation and a secondary winding permanently connected in multiple with said lamp and a relay responsive to the current flow in said secondary winding for disconnecting said discharge lamp from said operating transformer and for simultaneously effecting an energization of said lamp by said ionizing transformer during the starting period, and operable to connect said operating transformer to said lamp as soon as a predetermined current flows through said ionizing transformer winding.

3. In combination, an electric discharge lamp, an operating transformer, a second transformer having a primary winding connected in series with said lamp and a secondary winding connected in multiple with said lamp, and means responsive to current flow in said secondary winding arranged to connect said operating transformer across said primary winding when less than a predetermined current flows through said lamp and secondary winding, and to connect said operating transformer across said lamp and primary winding when such a predetermined current fiows through said lamp and said secondary winding.

JUSTIN PETERSON. 

